Production and characterisation of environmentally relevant microplastic test materials derived from agricultural plastics.

Soil environments across the globe, particularly in agricultural settings, have now been shown to be contaminated with microplastics. Agricultural plastics - such as mulching films - are used in close or direct contact with soils and there is growing evidence demonstrating that they represent a potential source of microplastics. There is a demand to undertake fate and effects studies to understand the behaviour and potential long-term ecological risks of this contamination. Yet, there is a lack of test materials available for this purpose. This study describes the manufacture and characterisation of five large (1-40 kg) batches of microplastic test materials derived from agricultural mulching films. Batches were produced from either polyethylene-based conventional mulching films or starch-polybutadiene adipate terephthalate blend mulching films that are certified biodegradable in soil. Challenges encountered and overcome during the micronisation process provide valuable insights into the future of microplastic test material generation from these material types. This includes difficulties in micronising virgin polyethylene film materials. All five batches were subjected to a thorough physical and chemical characterisation - both of the original virgin films and the subsequent microplastic particles generated - including a screening for the presence of chemical additives. This is a critical step to provide essential information for interpreting particle fate or effects in scientific testing. Trade-offs between obtaining preferred particle typologies and time and cost constraints are elucidated. Several recommendations emerging from the experiences gained in this study are put forward to advance the research field towards greater harmonisation and utilisation of environmentally relevant test materials.

Motor proteins at work for nanotechnology.

The biological cell is equipped with a variety of molecular machines that perform complex mechanical tasks such as cell division or intracellular transport. One can envision employing these biological motors in artificial environments. We review the progress that has been made in using motor proteins for powering or manipulating nanoscale components. In particular, kinesin and myosin biomotors that move along linear biofilaments have been widely explored as active components. Currently realized applications are merely proof-of-principle demonstrations. Yet, the sheer availability of an entire ready-to-use toolbox of nanosized biological motors is a great opportunity that calls for exploration.

Complications after a 5-year experience with laparoscopic donor nephrectomy: the Indiana University experience.

BACKGROUND: Laparoscopic donor nephrectomy (LDN) is becoming the standard of care for living donor nephrectomy. However, questions have been raised about the safety of LDN for the donor and about the potentially increased rates for ureteral complications experienced by the recipient. In this report, the authors review their 5-year experience with 253 living laparoscopic donor nephrectomies. METHODS: A retrospective chart review was performed for 253 laparoscopic live donors. Graft function and survival were compared using recipient postoperative creatinine values up to 12 months. RESULTS: The overall rate of complications in the investigated series was 10.3%. There were seven intraoperative complications (2.8%), three of which required open conversion. There were 19 postoperative complications (7.5%), three of which required reexploration for bleeding. The majority of complications were minor including 62% grade 1, 8% grade 2, 31% grade 3, and no grade 4 or 5 complications. There were no intraoperative complications in the right-sided donor group. There was a 5% complication rate for patients with a body mass index (BMI) exceeding 25. The findings showed that 11.2% of the recipients had slow graft function, and 4.4% had delayed graft function. Less than 1% of the recipients experienced ureteral stricture requiring permanent stent placement or reoperation. Overall, there was a 2% graft loss rate. CONCLUSIONS: The findings show a low rate of intraoperative and postoperative complications, most of which were minor complications. There was an increase in operative time and hospital stay in the right-sided group, but no increase in complication rate. There was no significant difference in outcome or complication rate for the overweight patients.

Laparoscopic donor nephrectomy: effects of learning curve on surgical outcomes.

UNLABELLED: Our objective was to determine the effect of an experienced laparoscopic surgeon's learning curve with laparoscopic donor nephrectomy (LDN) on patient outcome and graft function. MATERIALS AND METHODS: Retrospective review of the medical records of the initial 73 consecutive LDN patients and corresponding transplant recipients was performed. All of the LDN were performed by a single, experienced laparoscopic surgeon (C.P.S.). The method of LDN was slightly different between the groups. RESULTS: Patients were divided into early and late groups with 37 and 36 patients, respectively. There was no statistically significant difference in mean estimated blood loss (245 +/- 671.2 vs 84.7 +/- 63.9 mL), warm ischemia time (159.7 +/- 66.3 vs 150.8 +/- 63.0 seconds), postoperative creatinine levels (1.34 +/- 0.24 vs 1.29 +/- 0.26 mg/dL,), recipient mean creatinine level at 1 month (1.57 +/- .98 vs 1.53 +/- 0.46 mg/dL), and hospital stay (2.49 +/- 0.87 vs 2.47 +/- 0.56 days) between the early and late groups. However, the difference in mean operative time between early and late groups was statistically significant (255.2 +/- 42.4 vs. 209.1 +/- 30.8 minutes, P < .05). In addition, there were 8 (21.6%) vs 4 (11.1%) instances of slow graft function and 3 (8.1%) vs 0 instances of delayed graft function among the recipients in early group versus the late group. There were four (10.8%) vs two (5.6%) minor complications among donors of the early and late groups, respectively. CONCLUSION: There is a significant decrease in operating time and incidence of delayed graft function following the first 37 patients who underwent LDN by an experienced laparoscopist. Improvement in operative technique decreased operative time and improved perioperative graft function as evidenced by decreased slow graft function and delayed graft function in the late group.

Molecular sorting by electrical steering of microtubules in kinesin-coated channels.

Integration of biomolecular motors in nanoengineered structures raises the intriguing possibility of manipulating materials on nanometer scales. We have managed to integrate kinesin motor proteins in closed submicron channels and to realize active electrical control of the direction of individual kinesin-propelled microtubule filaments at Y junctions. Using this technique, we demonstrate molecular sorting of differently labeled microtubules. We attribute the steering of microtubules to electric field-induced bending of the leading tip. From measurements of the orientation-dependent electrophoretic motion of individual, freely suspended microtubules, we estimate the net applied force on the tip to be in the picoNewton range and we infer an effective charge of 12 e- per tubulin dimer under physiological conditions.

High rectifying efficiencies of microtubule motility on kinesin-coated gold nanostructures.

We demonstrate highly efficient rectification of microtubule motility on gold nanofabricated structures. First, we present a novel nanofabrication process for the creation of gold tracks for microtubule motility recessed in silicon oxide. This approach is particularly useful because it enables the use of the well-understood PEG-silane chemistry on SiO2 for the blocking of kinesin, whereas the gold tracks allow possible electrical control. We demonstrate excellent confinement of microtubule motility to the gold nanostructures and that microtubules move on the gold with speeds comparable to that on glass. Second, we present designs of three advanced rectifier geometries. We analyze the microtubule pathways through the geometries, and we demonstrate highly efficient rectification with up to 92% efficiency. As a result, we find that up to 97% of the microtubules move unidirectionally.

Electrical docking of microtubules for kinesin-driven motility in nanostructures.

We demonstrate localized electrical control of the docking of microtubules onto engineered kinesin-coated structures. After applying a voltage to a gold electrode, we observe an enhanced transport of microtubules from solution toward the surface and a subsequent increase of the amount of moving microtubule shuttles. Switching off the voltage leads to a partial detachment of microtubules from the surface. The surface coverage of microtubules, during both the docking and undocking events, follows an exponential time dependence. We provide a simple kinetic model, incorporating the equilibrium between free and surface-bound microtubules, that explains these data.

Matching training tasks to abilities of people with mental retardation: a learning test versus experienced staff.

Three sets of predictions were compared concerning the ability of 18 persons with severe or moderate mental retardation to learn 12 training tasks. Predictions were made by (a) experienced teachers who had worked with the clients for a minimum of 8 months and (b) experienced teachers who did not know the clients personally but who interacted with them for 30 minutes and by (c) consideration of client performance on the Assessment of Basic Learning Abilities test. To teach each task to a pass or fail criterion, we applied standard training procedures. The Assessment of Basic Learning Abilities test was significantly more accurate for predicting client performance than was either group of experienced staff. Implications for decreasing the high cost of unproductive training time were discussed.

A staff manual to help developmentally disabled persons improve their work habits and productivity.

In keeping with new directions for Behavior Modification, this article presents a treatment manual that has evolved over the past dozen or so years from our research program on vocational habilitation with developmentally disabled persons. The manual presents staff-managed and self-management strategies for helping these people improve work habits and productivity in various settings. The manual was written for front-line staff working with developmentally disabled clients. Strategies are presented as a checklist, making it easy to select the most appropriate components for each client and work setting. The guidelines are supported by research. The manual has been used in numerous training seminars, and feedback has been positive. In a workshop at the 1990 Conference of the Florida Association for Behavior Analysis, for example, mean rating of the manual by participants was 4.5 on a 5-point scale.

A practical staff management package for use in a training program for persons with developmental disabilities.

A staff management package was investigated for increasing and maintaining behavioral training skills of direct-care staff. Behaviors of three direct-care staff members were monitored while they conducted a prevocational program with 27 adult clients with severe or profound mental retardation. The intervention was an easy-to-apply checklist used weekly by a supervisor to give feedback to direct-care staff. The management procedure did not require the supervisor to collect quantitative data to be graphed or charted. Use of the checklist during a weekly morning work session in a multiple-baseline design across subjects led to immediate improvement in staff performance during daily morning work sessions. Considerable generalization of improved staff performance to daily afternoon work sessions with a different client group occurred. Further increases in staff performance occurred when the management procedure was added to afternoon work sessions. Staff performance was maintained over 4 months after the management procedure was decreased from weekly to biweekly use. When performance of direct-care staff improved, on-task behavior of most clients also substantially increased. Direct-care staff preferred the staff management package compared to "traditional" methods of supervision, and the training unit adopted the checklist for continuous use at the conclusion of the study.

Women as motivators in the use of safety belts.

A sample of rural and urban women was interviewed using a questionnaire based on Fishbein's and Ajzen's Theory of Reasoned Action. Two hundred women were asked about their intentions to use safety-belts and to encourage others to use safety-belts. Both intent and nonintent women highly valued saving lives, feeling safer, and reducing the likelihood of injuries, but they differed markedly in their beliefs that using safety-belts would necessarily save life, enhance their feeling of safety, and reduce the likelihood of injuries. Intent and nonintent users differed least in their beliefs that safety-belts would reduce injuries. Women who intended to use their safety-belts felt their action would encourage others to use belts and believed that they should encourage others to use their safety-belts. These intent safety-belt users did not see a strong social support for encouraging others to use safety belts and therefore were unlikely to do so. Programs to promote safety-belt use would capture the generally supportive attitudes of women if they could assist women to develop skills and confidence to express effectively their existing predisposition for safety-belt use.

A recruitment-of-praise package to increase productivity levels of developmentally handicapped workers.

This research examined the effectiveness of a recruitment package to increase production rates of three developmentally handicapped adults in a sheltered workshop. A baseline phase measured production rates of a paper-folding task under "typical" supervisory conditions. The recruitment package, introduced in a multiple-baseline design across subjects, involved goal setting by the experimenter, and self-monitoring, recruitment of praise, and self-delivery of a "happy face" by the worker. The recruitment package increased the production rates for two subjects, but decreased production rates for the third subject. Social validity data indicated that all subjects preferred the recruitment package, and staff continued to employ the recruitment package for two subjects when the formal research was terminated.

Expanded assessment for discrimination learning with mentally retarded persons: a practical strategy for research and training.

Practical and reliable instruments to assess basic discriminations by severely and profoundly retarded persons are almost nonexistent. Research findings were reviewed on an assessment instrument, the AVC Discrimination Test, which can be administered in approximately 30 minutes to assess basic position, visual, and auditory discriminations. This test can be used with severely and profoundly mentally retarded persons and is reliable and predictive of client performance in classroom learning, language, and vocational tasks. The advantages of expanding current baseline assessment practices to include the AVC Discrimination Test in research and training programs for persons with mental retardation were discussed.

Self-monitoring and self-managed reinforcement procedures for improving work productivity of developmentally disabled workers. A review.

This article reviews research that examined self-monitoring and/or self-managed reinforcement procedures for improving and maintaining work productivity of developmentally disabled workers. Seventeen articles were encountered that examined self-monitoring and/or self-administration of reinforcers for productivity. In total, 107 developmentally disabled persons experienced self-management procedures, with diagnoses varying from profoundly to mildly retarded. In most of the studies, work productivity improved during intervention conditions. However, in almost all cases, procedural limitations prevent us from confidently attributing improvements in productivity to the self-management components of the interventions. Moreover, because of practical limitations, we cannot yet offer self-management procedures as a viable strategy to maintain work rates of developmentally disabled workers at acceptable levels throughout typical working days. Additional research is needed that goes beyond the procedural and practical limitations of previous studies.

Self-management with picture prompts to improve quality of household cleaning by severely mentally handicapped persons.

A strategy was devised for measuring quality of household cleaning by four severely mentally handicapped adults living in a community residence. Two interventions were then compared for improving quality of cleaning. One intervention was a staff-managed graduated prompting system. The other intervention was a self-management package (SMP) made up of sequential picture cues, self-monitoring, feedback on performance after task completion, and public posting of results. Although the prompting system produced moderate improvements in three of the subjects (mean increase of 10%), the SMP was much more effective, producing large gains in three of four subjects (mean increase of 32% over prompting and 42% over baseline), resulting in acceptable levels of performance. Generalization to a no-treatment control task was quite limited. Follow-up indicated maintenance of improved performance over a 12-week interval with three of the four subjects.

Applying the theory of reasoned action to early adolescent tobacco chewing.

Beliefs and social norms elicited from adolescents were employed in the theory of reasoned action to predict early adolescent males' intention to chew tobacco. About 50% of males had chewed tobacco. Responses of chewing intenders and nonintenders differed in response direction and in response strength. Response differences regarding physical effects (cancer, yellow teeth, habit forming) as well as psychosocial effects (look cool, relax, have a good time with friends) suggested specific educational strategies. Intenders and nonintenders both reported not believing chewing causes cancer, an erroneous belief. Nonintenders reported belief carry over from smoking: chewing will "make my clothes smelly" and chewing will "give me shortness of breath," both unfounded. Nonintenders reported less referent support for chewing. Both groups reported a general unwillingness to comply with their significant others.

Late onset reactions in humans: correlation between skin and bronchial reactivity.

We carried out sequential measurements of the intensity of simultaneously occurring late onset skin and bronchial reactivity in seven atopic subjects following skin and inhalation challenge with pollen antigen. All subjects demonstrated dual bronchial and cutaneous reactions. Although the intensity of the late onset bronchial responses correlated temporally and quantitatively with the degree of increase in serum neutrophil chemotactic activity, the intensity of the late onset skin responses correlated with the level of specific antigen-IgE in the serum. This suggests that even in the same subjects, different factors govern the intensity of late onset skin and bronchial responses.